Sendaro

Sendaro is a transactional email API for sending password resets, receipts, sign-in links and notifications from your own domain. You verify a domain by publishing DKIM, SPF and DMARC DNS records, create an API key, and send with one REST request or an SDK call. A message ID is returned right away.

Each domain can have up to 10 sending subdomains, so newsletters or product updates can stay apart from receipts and password resets. There is no list or campaign builder. The product includes email logs with event history, signed webhooks, a metrics dashboard for volume, bounce and complaint rates, idempotency keys, a suppression list, scoped API keys and an OpenAPI spec.

An email is marked delivered only after the recipient's mail server confirms it.